Use QML TreeView in Assets Library

Task-number: QDS-7344
Change-Id: Ia1ea584fc7acabb0d35b745e36fef18799f21ab5
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/components/contentlibrary/contentlibraryview.cpp

@@ -55,7 +55,7 @@ WidgetInfo ContentLibraryView::widgetInfo()
                 // copy image to project
                 AddFilesResult result = ModelNodeOperations::addImageToProject({texPath}, "images", false);
 
-                if (result == AddFilesResult::Failed) {
+                if (result.status() == AddFilesResult::Failed) {
                     Core::AsynchronousMessageBox::warning(tr("Failed to Add Texture"),
                                                           tr("Could not add %1 to project.").arg(texPath));
                     return;